/***************************************************************************
 *  CompareFunctionSet.cs
 *
 *  Copyright (C) 2007 Novell, Inc.
 *  Written by Aaron Bockover <abockover@novell.com>
 ****************************************************************************/

/*  THIS FILE IS LICENSED UNDER THE MIT LICENSE AS OUTLINED IMMEDIATELY BELOW: 
 *
 *  Permission is hereby granted, free of charge, to any person obtaining a
 *  copy of this software and associated documentation files (the "Software"),  
 *  to deal in the Software without restriction, including without limitation  
 *  the rights to use, copy, modify, merge, publish, distribute, sublicense,  
 *  and/or sell copies of the Software, and to permit persons to whom the  
 *  Software is furnished to do so, subject to the following conditions:
 *
 *  The above copyright notice and this permission notice shall be included in 
 *  all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
 *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
 *  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 
 *  DEALINGS IN THE SOFTWARE.
 */

using System;

namespace SExpEngine
{
    public class CompareFunctionSet : FunctionSet
    {
        [Function("compare-to")]
        public virtual TreeNode OnCompareTo(TreeNode [] args)
        {
            if(args.Length != 2) {
                throw new ArgumentException("must have two arguments");
            }
            
            return Compare(Evaluator, args[0], args[1]);
        }

        public static TreeNode Compare(EvaluatorBase evaluator, TreeNode a, TreeNode b)
        {
            TreeNode arg_a = evaluator.Evaluate(a);
            TreeNode arg_b = evaluator.Evaluate(b);
            
            if(arg_a.GetType() != arg_b.GetType()) {
                throw new ArgumentException("arguments must be of the same type to compare");
            }
            
            int result = 0;
            
            if(arg_a is IntLiteral) {
                result = (arg_a as IntLiteral).Value.CompareTo(
                    (arg_b as IntLiteral).Value);
            } else if(arg_a is DoubleLiteral) {
                result = (arg_a as DoubleLiteral).Value.CompareTo(
                    (arg_b as DoubleLiteral).Value);
            } else if(arg_a is StringLiteral) {
                result = (arg_a as StringLiteral).Value.CompareTo(
                    (arg_b as StringLiteral).Value);
            } else if(arg_a is BooleanLiteral) {
                result = (arg_a as BooleanLiteral).Value.CompareTo(
                    (arg_b as BooleanLiteral).Value);
            } else {
                throw new ArgumentException("invalid type for comparison");
            }
            
            return new IntLiteral(result);
        }
        
        [Function("less-than", "<")]
        public virtual TreeNode OnCompareLessThan(TreeNode [] args)
        {
            IntLiteral result = (IntLiteral)OnCompareTo(args);
            return new BooleanLiteral(result.Value < 0);
        }
        
        [Function("greater-than", ">")]
        public virtual TreeNode OnCompareGreaterThan(TreeNode [] args)
        {
            IntLiteral result = (IntLiteral)OnCompareTo(args);
            return new BooleanLiteral(result.Value > 0);
        }
        
        [Function("equal", "=")]
        public virtual TreeNode OnCompareEqual(TreeNode [] args)
        {
            IntLiteral result = (IntLiteral)OnCompareTo(args);
            return new BooleanLiteral(result.Value == 0);
        }
        
        [Function("not-equal", "!=")]
        public virtual TreeNode OnCompareNotEqual(TreeNode [] args)
        {
            BooleanLiteral result = (BooleanLiteral)OnCompareEqual(args);
            return new BooleanLiteral(!result.Value);
        }
        
        [Function("less-than-or-equal", "<=")]
        public virtual TreeNode OnCompareLessThanOrEqual(TreeNode [] args)
        {
            BooleanLiteral a = (BooleanLiteral)OnCompareLessThan(args);
            BooleanLiteral b = (BooleanLiteral)OnCompareEqual(args);
            return new BooleanLiteral(a.Value || b.Value);
        }
        
        [Function("greater-than-or-equal", ">=")]
        public virtual TreeNode OnCompareGreaterThanOrEqual(TreeNode [] args)
        {
            BooleanLiteral a = (BooleanLiteral)OnCompareGreaterThan(args);
            BooleanLiteral b = (BooleanLiteral)OnCompareEqual(args);
            return new BooleanLiteral(a.Value || b.Value);
        }
    }
}
